first i made a selection of the sky using the colour range option, i think used brightness and contrast to make the sky dull.
step 2 of 3
then using the add noise filter, i made the snow and using levels adjustment i made it lessen, and also used the motion blur filter to make the effect of the falling.
step 3 of 3
i then duplicated my first snow image, and enlarged it, i then used the crystallize filter to make the affect of it being closer, and then i blurred it to give it a depth feel. after this i changed to opacity on my two snow layers to make it more realistic.